For more good times like Facebook.com/BjjBrick
This is true, you should not rely on your cup when you are doing an armbar. Squeeze your knees and hold the arm well before it gets to your cup. Get a deep armbar, be as close to the sholder as possible and away from the sharp elbow. Maintain control of the arm. These tips should help you have better armbars and not rely on your cup.
More good times Facebook.com/BjjBrick